The invention relates to pneumatic conveying and more specifically to conveying milled materials such as flour from one point to another by means of negative pressure. The invention, which is a blender fitting, is utilized in pneumatic conveying systems for blending high volumes of suction air with the milled stock as a means of conveying the milled stock from one location to another. Blender fittings also have the function of an overload release means, also referred to as an anti-choke dump valve, which automatically releases the milled material in the system when it chokes or clogs.